Semitransparent Flexible Organic Solar Cells Employing Doped-Graphene Layers as Anode and Cathode Electrodes

Shin, Dong Hwa; Jang, Chan Wook; Lee, Ha Seung; Seo, Sang Woo; Choi, Suk‐Ho

doi:10.1021/acsami.7b16730

Cited by 70 publications

(41 citation statements)

References 42 publications

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“…Although conventional opaque solar cells exhibit high efficiencies, they require dedicated space and additional installation efforts in the form of metal frame constructions on the roof or façade; a general disadvantage within the BIPV context ( Figure ). The research topic of semitransparent organic solar cells (OSCs) addresses the aforementioned issues by offering solutions, such as the implementation of flexible semitransparent OSCs into glass windows and roofs of new or existing buildings, greenhouses, vehicles, or mobile electronic devices, thereby transforming them into energy harvesting multifunctional units . Additionally, OSCs can be tuned to absorb specific frequencies such as UV, vis, or near‐IR and they can be easily integrated with other devices, such as to drive electrochromic devices that modulate the level of interior light …”

Section: Introductionmentioning

confidence: 99%

Solution‐Processed Semitransparent Organic Photovoltaics: From Molecular Design to Device Performance

et al. 2019

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Recent research efforts on solution-processed semitransparent organic solar cells (OSCs) are presented. Essential properties of organic donor:acceptor bulk heterojunction blends and electrode materials, required for the combination of simultaneous high power conversion efficiency (PCE) and average visible transmittance of photovoltaic devices, are presented from the materials science and device engineering points of view. Aspects of optical perception, charge generation-recombination, and extraction processes relevant for semitransparent OSCs are also discussed in detail. Furthermore, the theoretical limits of PCE for fully transparent OSCs, compared to the performance of the best reported semitransparent OSCs, and options for further optimization are discussed. Hall of Fame ArticleAlthough the last decade has seen much progress in the field of OSC research, the development of semitransparent devices lags behind because of the lack of optimized photoactive materials. [22][23][24][25] The strong absorption of the active materials in the visible region causes difficulty when one tries to balance the power conversion efficiency (PCE) and transmittance. Encouragingly, the recent progress of fullerene-free OSCs has the potential to shed fundamental solutions to overcome these obstacles, hence becoming attractive research topics on developing narrow-bandgap nonfullerene acceptors to researchers. [26][27][28][29][30] We focus in this section on presenting recent progress in the design of narrow-bandgap organic semiconductors that have bandgaps less than 1.5 eV and have extended the boundaries of visible transparent/NIR absorbing OSC technology. Solution-Processable Organic SemiconductorsOrganic semiconductors are carbon-based materials with an electronically delocalized π-conjugated backbone. Such π-conjugated systems are created by a linear series of overlapping p z orbitals (π bonds). [31,32] As the parallel overlap of carbon p z orbitals increases with the molecular extension, the π bonds may further spread out into π bands, and this leads to a narrower energy bandgap. The energy of the highest occupied molecular orbital (HOMO) corresponds to the topmost π band, and the lowest π* band is referred to as the lowest unoccupied molecular orbital (LUMO). The energy gap between the HOMO and the LUMO dominates optical properties. Photoexcitations result in Coulombically bound excitons (electron-hole pairs) due to the low dielectric constant (ε ≈ 2−4) characteristic of organic semiconductors. [33,34] The exciton binding energy is in the range of 0.3−1 eV, thus requiring a high interfacial area between electron donor (D) and electron acceptor (A) components to promote exciton dissociation into free carriers. [35,36] This approach has led to the development of organic bulk heterojunctions (BHJs), which are cast from blend solutions of D and A components. [37][38][39] The excitonic nature of organic semiconductors offers an advantage in wavelength-specific light harvesting applications through a delicate manipulation of energy ...

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Section: Introductionmentioning

confidence: 99%

Solution‐Processed Semitransparent Organic Photovoltaics: From Molecular Design to Device Performance

et al. 2019

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“…The 0.2 cm 2 graphene devices with the 30 nm MoO x interfacial layer had an average PCE of 5.2% with V oc = 0.87 V, J sc = 11.5 mA cm −2 , and FF = 51%. Taking into account the device dimensions, a PCE of 5.2% is amongst the best performance for OSCs with a graphene‐based anode, noting that previously reported devices are generally smaller . However, we found that there was still a performance gap between the devices containing the graphene TCEs and the control ITO‐based devices, which showed an averaged PCE of 8.7%, with a J sc of 14.1 mA cm −2 , a V oc of 0.88 V, and a FF of 69%.…”

Section: Resultsmentioning

confidence: 46%

Graphene‐Based Transparent Conducting Electrodes for High Efficiency Flexible Organic Photovoltaics: Elucidating the Source of the Power Losses

et al. 2019

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Solution processed flexible organic solar cells (OSCs) are of interest due to their potential use as environmentally friendly, shapeable, or wearable energy. Such flexible devices require compatible transparent conducting electrodes (TCEs). The use of three-layer graphene as a useful TCE for flexible OSCs is reported. The conformal coating of the graphene-based TCE with good retention of performance was achieved using a bulk heterojunction (BHJ) active layer comprised of the nonpolymeric molecular (5Z,2 0 :5 0 ,2 00 :5 00 ,2 000 -quaterthiophene]-5 000 ,5-diyl})bis(methanylylidene)]bis[3-n-hexyl-2thioxothiazolidin-4-one] (BQR) donor and [6,6]-phenyl-C 71 -butyric acid methyl ester (PC 71 BM) as the acceptor. This material combination enables thick BHJ junctions to be used so that the roughness of the graphene surface did not lead to shorted devices. The best graphene/poly(ethylene terephthalate) (PET) devices (PET/ graphene/molybdenum oxide/BHJ/calcium/aluminum) show a photoconversion efficiency (PCE) of 5.8%, which while excellent was lower than that of a similar device architecture that used ITO/glass as the anode. The power losses of the graphene/PET-based cells mainly resulted from absorption losses caused by the optical profile distribution in the device and the relatively high sheet resistance of the anode, leading to an 18% decrease in the short-circuit current and lower fill factor, respectively.

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“…Later, Shin et al fabricated semitransparent flexible OSCs using bis‐(trifluoromethanesulfonyl)‐amide (TFSA) and triethylene tetramine (TETA)‐doped graphene as anode and cathode, respectively (Figure 4b). [ 72 ] The PCE was further improved to 4.23% by adding an Al reflective mirror on the side of the device. The flexible device retained more than 99% of the initial PCE after the bending test with a radius of 12–6 mm.…”

Section: Flexible Organic Solar Cellsmentioning

confidence: 99%

Recent Progress in Flexible and Stretchable Organic Solar Cells

Qin

Lan

Chen

et al. 2020

Adv Funct Materials

149

124

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Flexible and stretchable organic solar cells (OSCs) have attracted enormous attention due to their potential applications in wearable and portable devices. To achieve flexibility and stretchability, many efforts have been made with regard to mechanically robust electrodes, interface layers, and photoactive semiconductors. This has greatly improved the performance of the devices. State‐of‐the‐art flexible and stretchable OSCs have achieved a power conversion efficiency of 15.21% (16.55% for tandem flexible devices) and 13%, respectively. Here, the recent progress of flexible and stretchable OSCs in terms of their components and processing methods are summarized and discussed. The future challenges and perspectives for flexible and stretchable OSCs are also presented.

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Semitransparent Flexible Organic Solar Cells Employing Doped-Graphene Layers as Anode and Cathode Electrodes

Cited by 70 publications

References 42 publications

Solution‐Processed Semitransparent Organic Photovoltaics: From Molecular Design to Device Performance

Solution‐Processed Semitransparent Organic Photovoltaics: From Molecular Design to Device Performance

Graphene‐Based Transparent Conducting Electrodes for High Efficiency Flexible Organic Photovoltaics: Elucidating the Source of the Power Losses

Recent Progress in Flexible and Stretchable Organic Solar Cells

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